A refrigerator will keep food cold for about 4 hours if the door is kept closed.

A full freezer will keep temperature for about 48 hours (24 hours if half-full). If your freezer is not full, group packages so they form an “igloo” to protect each other. Place them to one side or on a tray so that if they begin thawing, their juices won’t get on other foods.

With frozen food: check for ice crystals! The food in your freezer that partially or completely thaws before power is restored may be safely refrozen if it still contains ice crystals or is 40 °F or below.

When the power comes back on, you will have to evaluate each item separately. When in doubt, throw it out.

If the power is going to be out for an extended period of time, buy dry or block ice to keep the refrigerator as cold as possible. Fifty pounds of dry ice should keep a fully-stocked 18-cubic-feet freezer cold for two days.

Don’t place frozen foods outside in the snow.

If your power is out due to a snowstorm, the sun’s rays can thaw frozen food even when the temperature is very cold. In addition, animals could discover your stash. Instead, take advantage of the cold temperatures by making ice outside. Fill buckets, empty milk cartons, or cans with clean water and leave them outside to freeze. Then put the “homemade ice” in your refrigerator, freezer, or coolers.

This will take away the guesswork of just how cold the unit is because it will give you the exact temperature. The key to determining the safety of food in the refrigerator and freezer lies in knowing how cold they are.

Discard any food that has an unusual odor, color, or texture, or feels warm to the touch.

Food safety questions? “Ask Karen,” the FSIS virtual representative available 24 hours a day at www.AskKaren.gov, or call the toll-free USDA Meat and Poultry Hotline at 1-888-MPHotline (1-888-674-6854).The Hotline is available in English and Spanish and can be reached from l0 a.m. to 4 p.m. ET Monday through Friday. Recorded food safety messages are available 24 hours a day.